In all species of pycnogonids (sea spiders) males care exclusively for the
offspring, making this group essential for studies on sex roles, sexual selection, and the
evolution of parental investment. Unfortunately, little is known about pycnogonid
mating patterns, larval development, or the costs associated with parental care. The
mating habits of both male and female Achelia simplissima were studied experimentally
and reveal that both sexes routinely mate multiple times and have multiple mates.
Parental males experience higher frequencies of predator attacks and epibionts and a
lower rate of movement as compared with nonparental males. However, parental males
are harder to dislodge than nonparental males and suffer no change in feeding frequency
as a result of parental care. The external morphology of the first larval stage of Achelia
simplissima was described using SEM photos and compared with other larval pycnogonids. Morphological characteristics suggest a "parasitic" mode of postembryonic
development.

Description:

x, 97 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.